Marie Ann Thiébaud appears to be the reason for the split between Shania Twain and husband Mutt Lange.

But sources close to the situation told People that Marie Ann Thiébaud, a longtime secretary and manager of the couple’s chateau in Switzerland, was at the center of the break-up.

“Mutt and Marie Ann left their spouses for each other and are still in a relationship,” one source told People.

“It’s absolutely not the reason [for the separation],” the famously reclusive producer told People when asked about the alleged affair. He also denied that he was in a romantic relationship with Thiébaud: “I’m not, no,” he said. “It’s not true.”

Twain and Lange announced last week that they were splitting after 14 years of marriage.

If Mutt left Shania for Marie Ann Thiebaud then he is one dumb and dirty dog!